1. Field of the Invention
The present invention relates to an X-ray computed tomographic apparatus and an image processing apparatus which generate tomographic image data based on projection data acquired by scanning a subject by means of X-rays.
2. Description of the Related Art
In recent years, in an X-ray computed tomographic apparatus, with advancement of practical use of volume scan (referred to as a cone beam scan) due to helical scan or multiply arrayed X-ray detectors, a wide range of data has been successfully acquired in a short time. In such a situation, unlike a conventional technique, instead of carrying out scanning in a scan range according to a reconstruction range which has been set in advance, it is believed that there will be an increasing demand for a technique for setting a reconstruction condition or a reconstruction range after scanning to reconstruct an image. Processing for reconstructing an image by setting the reconstruction condition or reconstruction range after scanning is referred to as batch reconstruction processing in order to discriminate processing for speedily reconstructing an image immediately after scanning the reconstruction condition or reconstruction range which has been set in advance. In the batch reconstruction processing, in order to set the reconstruction range, an axial image is displayed together with a scanogram, as shown in FIG. 8. The range in a body axis direction is specified on the scanogram, and the range in two directions orthogonal to the body axis is specified on the axial image.
The scanogram is a projection image, and moreover, is low in resolution, and thus, a morphological structure is hardly recognized. Thus, an axial image check is made in order to finally determine the range in the body axis direction. While switching axial images, namely, while moving a slice position of the axial image along the body axis, an operator checks the morphological structure in detail, and finally determines the range in the body axis direction. In this method, operability is very poor, and a large amount of tine interval is required to set the reconstruction range.